Pharmaceutical propylene glycol solvate compositions

ABSTRACT

The invention relates to pharmaceutical compositions comprising propylene glycol solvates of APIs.

CROSS REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This application is a divisional of U.S. Ser. No. 12/839,550 filed Jul. 20, 2010, which is a divisional of U.S. Ser. No. 10/747,742, filed Dec. 29, 2003, now U.S. Pat. No. 7,790,905, which claims the benefit of U.S. Provisional Application No. 60/486,713, filed Jul. 11, 2003, U.S. Provisional Application No. 60/459,501, filed Apr. 1, 2003, U.S. Provisional Application No. 60/456,608, filed Mar. 21, 2003, U.S. Provisional Application No. 60/456,027, filed Mar. 18, 2003, and U.S. Provisional Application No. 60/441,335, filed Jan. 21, 2003. The content of each of these applications is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to drug-containing compositions, pharmaceutical compositions comprising such drugs, and methods for preparing same.

BACKGROUND OF THE INVENTION

Drugs in pharmaceutical compositions can be prepared in a variety of different forms. Such drugs can be prepared so as to have a variety of different chemical forms including chemical derivatives or salts. Such drugs can also be prepared to have different physical forms.

For example, the drugs may be amorphous or may have different crystalline polymorphs, perhaps existing in different solvation or hydration states. By varying the form of a drug, it is possible to vary the physical properties thereof. For example, crystalline polymorphs typically have different solubilities from one another, such that a more thermodynamically stable polymorph is less soluble than a less thermodynamically stable polymorph. Pharmaceutical polymorphs can also differ in properties such as shelf-life, bioavailability, morphology, vapor pressure, density, color, and compressibility. Accordingly, variation of the solvation state of a drug is one of many ways in which to modulate the physical properties thereof.

A solvate may be defined as a compound formed by solvation, for example as a combination of solvent molecules with molecules or ions of a solute. Well known solvent molecules include water, alcohols and other polar organic solvents. Alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and t-butanol. Alcohols also include polymerized alcohols such as polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol). The best-known and preferred solvent is typically water, and solvate compounds formed by solvation with water are termed hydrates.

Propylene glycol (1,2-propanediol) is a known substance which is a liquid at ambient temperature. As far as the applicants are aware, propylene glycol is not generally well-known for use in the formation of solvates. U.S. Pat. No. 3,970,651 does disclose the use of propylene glycol in the formation of a crystalline cephalosporin derivative. According to this disclosure a propylene glycolate derivative of a specific cephalosporin zwitterion may be formed in the presence of propylene glycol at acidic pH. This disclosure indicates that the propylene glycol derivative is more stable in solid form than the corresponding ethanolate, especially having excellent colour stability and thermal stability. No other solvates are disclosed in this US patent other than the specific solvate of cephalosporin.

In pharmaceutical formulations certain chemical classes of drugs pose particular problems in preparing pharmaceutical formulations for medical use. One such problem arises in the case of hygroscopic drugs, which tend to absorb water from the air. This is disadvantageous because it makes storage of the drug difficult and can cause degradation of the drug in some cases. Such compounds must be handled in controlled humidity environments during manufacture in order to prevent potency errors due to the changing weight of the drug. The final product must be packaged in individual moisture resistant blisters in order to prevent changes in or degradation of the product. Another problem arises from variable hydration states: molecules may change to a more or less stable form as water, a volatile liquid, is lost. Such changes have been known to cause some hydrates to become amorphous. Likewise, absorption of water by a hygroscopic molecule can plasticise the system and lead to recrystallization as a less stable polymorph.

SUMMARY OF THE INVENTION

Solvates are rarely used in pharmaceuticals because the solvents are usually volatile thus making it difficult to maintain the solvent in the crystal. If one were to desolvate a pharmaceutical solvate or if it desolvated due to storage conditions or otherwise, it could lead to the formation of multiple polymorphs or complete collapse of the crystal structure, forming an amorphous compound with different physical properties. Obviously, this batch-to-batch variability and questionable shelf life is undesired. Typically people find solvates of common solvents, such as propanol and ethanol. Propylene glycol is similar in structure to propanol, but is not thought of as a solvent. Propylene glycol solvates of the present invention desolvate only at considerably higher temperatures and harsher conditions than traditional solvates. Propylene glycol solvates are also pharmaceutically acceptable in much larger amounts than one would expose people to with a traditional solvate. Thus, the propylene glycol solvates of the present invention have characteristics that are vastly superior to traditional solvates.

It has now been found that amorphous, crystalline, hygroscopic, or poorly soluble drugs can be made more soluble, more stable, and less hygroscopic and can be prepared simply, reliably and inexpensively.

In a first aspect, the present invention provides a pharmaceutical composition comprising a propylene glycol solvate of a drug which is hygroscopic or has low aqueous solubility.

It has surprisingly been found that by using propylene glycol to form a solvate of a hygroscopic drug, the hygroscopicity of the drug is decreased and/or the stability and aqueous solubility is increased. The drug is therefore much easier to formulate and store than its counterpart untreated or hydrated form.

A number of advantages have been found from the use of propylene glycol in this way. First of all, a higher temperature is required to remove propylene glycol as compared with water or ethanol. This therefore results in an increased thermal stability. Thus the invention further relates to methods of making a pharmaceutical solvate more stable at high temperatures by making a PG solvate of the drug. Secondly, propylene glycol solvates are generally more pharmaceutically acceptable than other common solvates, including those formed from alcohols other than ethanol. It has further been found that the PG solvates of the present invention have fewer solvation states than hydration states. This is beneficial because production and quality of a drug can be more predictable and consistent. Thus an aspect of the present invention relates to methods of reducing the number of hydration states by making a PG solvate of a drug. PG solvates are also beneficial in addressing the problem of polymorphism. Thus an aspect of the present invention relates to methods of reducing the rate and extent a drug changes form and methods of reducing the chance of making an unwanted form because the PG solvates drive production of a single form. Another aspect of the present invention relates to changing the crystal habit of the drug crystal and preventing a drug crystalline habit from changing to a different habit.

The invention relates to making a pharmaceutical that can be made as a hydrate, more soluble or stable by forming a PG solvate of the drug.

The invention further relates to making a pharmaceutical more stable in a humid environment by making a PG solvate of the drug.

The invention further relates to making a crystalline compound from a pharmaceutical that does not readily crystallize by making a crystalline PG solvate of the drug.

The invention further relates to increasing the solubility of a crystalline pharmaceutical by making a PG solvate of the drug.

The invention further relates to methods of lowering the amount of drug solvation during wet granulation by making a PG solvate of the drug.

A particularly important aspect of the present invention is the realization that formation of propylene glycol solvates is applicable in a general way to drugs whereby the above advantages may be conferred. For example, the invention further relates to reducing the level of hygroscopicity of a pharmaceutical metal salt (crystalline, amorphous, solvate (e.g., hydrate)) by forming a PG solvate of the salt. Surprisingly, it has been found that the invention is particularly applicable to those drugs that are in the form of metal salts, such as alkali metal or alkaline earth metal salts. This is especially the case where the metal is selected from sodium, potassium, lithium, calcium and magnesium. Such salts can be hygroscopic and it has hitherto been difficult to find a suitable general means of formulation for these drugs.

Generally, the molar ratio of propylene glycol to drug in the solvate is in the range 0.5 to 2, (e.g., 0.5, 1.0, 1.5, 2.0). Depending on the nature of the drug, the ratio of propylene glycol to drug in the solvate may be approximately 0.25, 0.33, 0.5, 0.67, 0.75, 1.0, 1.5, 2.0 or 3.0.

The composition may further comprise a pharmaceutically-acceptable diluent, excipient or carrier and details of pharmaceutical compositions are also set out in further detail below. The solvate of the pharmaceutical composition according to the present invention is preferably in a crystalline form.

Advantageously, the powder X-ray (PXRD) diffraction spectrum of the composition according to the invention differs from the corresponding powder X-ray diffraction spectrum of unsolvated drug by at least one property selected from:

(i) a loss of at least one peak;

(ii) shifting of more than half the peaks at the 2-theta angle by at least 0.2, 0.3, 0.4, or 0.5 degrees; or

(iii) formation of at least one new peak.

It is preferred that the solvate is stable to temperatures of up to 50 degrees C. under a stream of nitrogen gas in a thermogravimetric analysis apparatus.

The PXRD could be the same if their were a host-guest relationship and the PG was not completely frozen out. This would be an inclusion compound rather than a true solvate, but it may still be less hygroscopic than a hydrate, less prone to solvent loss than an inclusion with ethanol, less prone to being filled by some toxic co-solvent if PG fits well, and less prone to polymorphism to a less soluble form due to instability caused by a vacated void in the structure. The DSC transitions are likely to occur at different temperatures and have different intensities than for the parent molecule and it's other hydrates/solvates.

In one aspect of the invention, the drug is a hygroscopic drug, including hygroscopic metal salts. A non-exhaustive list of hygroscopic drugs is set out in Table 1, along with their suppliers and routes of administration.

TABLE 1 Hygroscopic Drugs Route(s) of Product (company) Active ingredient Hygroscopic Administration Solu-Medrol (P&U) Methyl prednisolone X Intravenous succinate ester Primaxin IV and IM Imipenem/cilastatin X (cilastatin) Intravenous/ (Merck) Intramuscular Vitravene Injection (CIBA) Fomivirsen sodium X Intravenous Baycol (Bayer) Cerivastatin sodium X Oral Synercid IV (Aventis) Dalfopristin/Quinopristin X Intravenous Factrel (Wyeth) Gonadorelin HCl X Intravenous/ (decapeptide) Subcutaneous Clindets Pledgets (Stiefel) Clindamycin phosphate X Topical (ester prodrug) Famvir (SKB) Famciclovir X Oral Nascobal Gel (Schwarz) Cyanocobalamin X Intranasal Tasmar (Roche) Tolcapone X Oral Ellence Injection (P&U) Epirubicin HCl X Intravenous Colestid (P&U) Colestipol HCl (anion X Oral excluded) Pfizerpen Injection (Pfizer) Penicillin G potassium X Intravenous Bacitracin Injection Bacitracin (peptide) X Intravenous (Paddock) Lescol (Novartis) Fluvastatin sodium X Oral Voltaren XR (Novartis) Diclofenac sodium X Oral Salagen (MGI) Pilocarpine HCl X Oral Urecholine injection Bethanechol chloride X Intravenous (Merck) Syprine (Merck) Trientine 2(HCl) X Oral Singulair chewable (Merck) Montelukast sodium X Oral Mustargen injection Mechlorethamine HCl X Intravenous (Merck) Hydrocortone phosphate Hydrocortisone X Intravenous injection (Merck) phosphate ester Decadron phosphate Dexamethasone X Intravenous injection (Merck) phosphate ester Gastrocrom (Medeva) Chromolyn sodium X Oral Mestinon (ICN) Pyridostigmine X Oral bromide Adipex-P (Gate) Phentermine HCl X Oral Micardis (Boehringer- Telmisartan X Oral Ingelh.) Cerubidine injection Daunorubicin HCl X Intravenous (Bedford) Biltricide (Bayer) Praziquantel X Oral Elmiron (Alza) Pentosan polysulfate X Oral sodium

In one embodiment, the formulation comprises celecoxib. Although the invention is not limited to this particular drug, celecoxib provides a suitable example of the efficacy of the invention. Further details of celecoxib are set out below. In a further embodiment, the drug comprises naproxen, further details of which are also set out below.

In another aspect of the invention, the drug has low aqueous solubility. Typically, low aqueous solubility in the present application refers to a compound having a solubility in water which is less than or equal to 10 mg/ml, when measured at 37 degrees C., and preferably less than or equal to 5 mg/ml or 1 mg/ml. “Low aqueous solubility” can further be defined as less than or equal to 900, 800, 700, 600, 500, 400, 300, 200 150 100, 90, 80, 70, 60, 50, 40, 30, 20 micrograms/ml, or further 10, 5 or 1 micrograms/ml, or further 900, 800, 700, 600, 500, 400, 300, 200 150, 100 90, 80, 70, 60, 50, 40, 30, 20, or 10 ng/ml, or less than 10 ng/ml when measured at 37 degrees C. Aqueous solubility can also be specified as less than 500, 400, 300, 200, 150, 100, 75, 50 or 25 mg/ml. As embodiments of the present invention, solubility can be increased 2, 3, 4, 5, 7, 10, 15, 20, 25, 50, 75, 100, 200, 300, 500, 750, 1000, 5000, or 10,000 times by making a PG solvate of the neutral (crystalline or amorphous), salt, or solvate form (e.g., hydrate, ethanolate, methanolate, isopropanolate, etc.). Further aqueous solubility can be measured in simulated gastric fluid (SGF) rather than water. SGF (non-diluted) of the present invention is made by combining 1 g/L Triton X-100 and 2 g/L NaCl in water and adjusting the pH with 200 mM HCl to obtain a solution with a final pH=1.7.

PG solvates of steroids are also included as embodiments of the present invention. Steroids are an important class of drugs which have low aqueous solubility. Particularly important steroids include acetoxypregnenolone, alclometasone dipropionate, aldosterone, anagestone, norethynodrel, androsterone, betamethasone, budesonide, chlormadinone, chloroprednisone, corticosterone, cortisone, cyclosporine, desogestrel, desoximethasone, desoxycorticosterone, dexamethasone, dichlorisone, dimethisterone, equilenin, equilin, estradiol, estriol, estrogens, estrone, ethisterone, ethynodiol di, ethynyl estradiol, fludrocortisone, fludrocortisone, flunsolide, fluocinolone acetonide, fluorohydrocortisone, fluorometholone, fluoxymesterone, fluprednisolone, flurandrenolide, flurandrenolone, fluorogestone, fluticasone propionate, hydrocortisone, hydroxydion, hydroxymethylprogesterone, hydroxyprogesterone, leuprolide, levonorgestrel, loteprednol etabonate, medroxyprogesterone, melengestrol, mesalamine, mestranol, methandrostenolone, methazolamide, methyl testosterone, methylandrostenediol, methylprednisolone, mometasone furoate, norelgestromin, norethandrolone, norethindrone, norethindrone, norethisterone, norgestimate, norgestrel, normethisterone, ondansetron hydrochloride, oxandrolone, oxymetholone, paramethasone, paramethasone, prednisolone, prednisolone, prednisone, pregnenolone, progesterone, prometholone, spironolactone, testosterone, testosterone enanthate, triamcinolone, triamcinolone acetonide, triamcinolone acetonide, vetamethasone disodium phosphate (for some steroids alternative names are included). Formulating steroid drugs presents a problem because of their low aqueous solubility. Embodiments of the present invention are methods of increasing the solubility of steroids by making a PG solvate. Solubility can be specified as discussed above. It is difficult to make crystals of steroids because of their planar structure. Crystallization can be facilitated by making PG solvates. Thus, crystalline PG solvates of steroids and methods of making the same are included in embodiments of the present invention. Steroids generally tend to form non-stoichiometric channel hydrates in which water molecules are trapped in channels between planar steroid regions. Thus, embodiments of the present invention include inhibiting channel formation in steroids by making a PG solvate. Metal salts of steroid drugs can be made and are another example of hygroscopic drugs. Thus, steroid PG solvates are in accordance with one aspect of the present invention. Steroid drugs, whether hygroscopic or not, surprisingly and advantageously form stoichiometric solvates with propylene glycol. Further, the dissolution rate and solubility can be increased with propylene glycol solvates. Thus, the steroid solvates have surprisingly new properties that make them more favourable for pharmaceutical use and are easier to handle than other forms such as hydrates.

In a further aspect, the present invention provides a method for preparing a propylene glycol solvate of a drug, which method comprises:

(a) contacting propylene glycol with a drug in solution; (b) crystallizing a propylene glycol solvate of the drug from the solution; and (c) isolating the solvate. (the drug may be, for example, a hygroscopic drug or a drug of low aqueous solubility).

In a further aspect, the present invention provides a method for decreasing the hygroscopicity of a drug, which method comprises:

(a) contacting the drug with propylene glycol in solution; (b) crystallizing a propylene glycol solvate of the drug from the solution; and (c) isolating the solvate, wherein the solvate has decreased hygroscopicity as compared to the drug.

In a further aspect, the present invention provides a method for increasing the aqueous solubility of a drug, which method comprises:

(a) contacting the drug with propylene glycol in solution; (b) crystallizing a propylene glycol solvate of the drug from the solution; and (c) isolating the solvate, wherein the solvate has increased aqueous solubility as compared to the drug.

Typically, conditions for making a solvate are the same as for preparing the corresponding non-solvated form of the drug: the solvate of neutral compound would not be pH controlled; the solvate of an acid addition salt would be prepared by including PG with the drug and the acid; and the solvate of a base addition salt would involve adding the drug, the desired base, and the PG. Different co-solvent systems, anti-solvents, or temperature conditions may be used to encourage PG solvate formation. Seed crystals may be added if they have previously been prepared and isolated.

The step of isolating the solvate may include separating the solution phase from the solvate. Any common method of separation may be employed, including filtration and decanting. The crystalline solvate may be rinsed one or more times with an appropriate solvent following filtration or decanting. The crystalline solvate is preferably dried to remove excess solution phase. Drying may be carried out by thermal processing, vacuum, blowing a stream of gas such as air, nitrogen, argon or another inert gas, or a combination of any or all of these methods. The intention of the rinsing and drying steps is to remove impurities including residual co-solvents and excess PG, acid, or base if used.

The invention will now be described in further detail, by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a thermogravimetric analysis of a propylene glycol solvate of a celecoxib sodium salt.

FIG. 2A-D shows the PXRD pattern of a propylene glycol solvate of a celecoxib sodium salt.

FIG. 3 shows a thermogravimetric analysis of a propylene glycol solvate of a celecoxib potassium salt.

FIG. 4 shows the PXRD pattern of a propylene glycol solvate of a celecoxib potassium salt.

FIG. 5 shows a thermogravimetric analysis of a propylene glycol solvate of a celecoxib lithium salt.

FIG. 6 shows the PXRD pattern of a propylene glycol solvate of a celecoxib lithium salt.

FIG. 7 shows the thermogravimetric analysis of a propylene glycol solvate of naproxen sodium salt.

FIG. 8 shows a PXRD pattern of a propylene glycol solvate of naproxen sodium salt.

FIG. 9 shows the thermogravimetric analysis of a propylene glycol solvate of olanzapine form I.

FIG. 10 shows the differential scanning calorimetry thermogram of a propylene glycol solvate of olanzapine form I.

FIG. 11A-B shows PXRD patterns of a propylene glycol solvate of olanzapine form I.

FIG. 12 shows a packing diagram of olanzapine form I PG solvate.

FIG. 13 shows the thermogravimetric analysis of a propylene glycol solvate of cortisone acetate.

FIG. 14 shows the differential scanning calorimetry thermogram of a propylene glycol solvate of cortisone acetate.

FIG. 15A-B shows PXRD patterns of a propylene glycol solvate of cortisone acetate.

FIG. 16 shows a PXRD pattern of cortisone acetate.

FIG. 17 shows a packing diagram of cortisone acetate PG solvate.

FIG. 18 shows the thermogravimetric analysis of a trihydrate of celecoxib sodium PG solvate.

FIG. 19 shows the PXRD pattern of a trihydrate of celecoxib sodium PG solvate.

FIG. 20 shows the thermogravimetric analysis of a trihydrate of celecoxib sodium PG solvate.

FIG. 21 shows the PXRD pattern of a trihydrate of celecoxib sodium PG solvate.

FIG. 22 shows the PXRD pattern of celecoxib sodium salt.

FIG. 23 shows the PXRD pattern of celecoxib lithium salt.

FIG. 24 shows the PXRD pattern of celecoxib potassium salt.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to propylene glycol solvate forms, preferably stoichiometric, of certain drugs, including those which are hygroscopic or have low aqueous solubility. Whilst the invention is applicable to any such drugs in general, metal salts of the non-steroidal anti-inflammatory drug celecoxib serve to illustrate the present invention by way of example. Unlike traditional non-steroidal anti-inflammatory drugs (NSAIDs), celecoxib is a selective inhibitor of cyclooxygenase II (COX-2) which causes fewer side effects when administered to a subject. The present applicants have identified new forms of celecoxib that have improved properties, particularly as oral formulations. The applicants have found that a stable, crystalline sodium salt of celecoxib can be synthesised which is significantly more soluble in water than the neutral celecoxib on the market. This sodium salt, or other metal salts can subsequently be improved according to the present invention by the production of a propylene glycol solvate thereof.

Salts of celecoxib are formed by reaction of celecoxib with an acceptable base. Acceptable bases include, but are not limited to, metal hydroxides and alkoxides with sufficiently high pK_(a)'s (e.g., pK_(a)'s greater than about 11 to about 12). Naproxen is a further API which may be used to illustrate the present invention.

Naproxen is a member of the ibufenac group of NSAIDs. This API is practically insoluble in water. Other examples of illustrations of the present invention include olanzapine and cortisone acetate.

An aspect of the present invention provides a pharmaceutical composition comprising a propylene glycol solvate of a drug that is less hygroscopic than the amorphorous, neutral crystalline, or salt crystalline form, and/or has greater aqueous solubility. Hygroscopicity should be assessed by dynamic vapor sorption analysis, in which 5-50 mg of the compound is suspended from a Cahn microbalance. The compound being analyzed should be placed in a non-hygroscopic pan and its weight should be measured relative to an empty pan composed of identical material and having nearly identical size, shape, and weight. Ideally, platinum pans should be used. The pans should be suspended in a chamber through which a gas, such as air or nitrogen, having a controlled and known percent relative humidity (% RH) is flowed until eqilibrium criteria are met. Typical equilibrium criteria include weight changes of less than 0.01% change over 3 minutes at constant humidity and temperature. The relative humidity should be measured for samples dried under dry nitrogen to constant weight (<0.01% change in 3 minutes) at 40 degrees C. unless doing so would de-solvate or otherwise convert the material to an amorphous compound. In one aspect, the hygroscopicity of a dried compound can be assessed by increasing the RH from 5 to 95% in increments of 5% RH and then decreasing the RH from 95 to 5% in 5% increments to generate a moisture sorption isotherm. The sample weight should be allowed to equilibrate between each change in % RH. If the compound deliquesces or becomes amorphous between above 75% RH, but below 95% RH, the experiment should be repeated with a fresh sample and the relative humidity range for the cycling should be narrowed to 5-75% RH or 10-75% RH instead of 5-95% RH. If the sample cannot be dried prior to testing due to lack of form stability, than the sample should be studied using two complete humidity cycles of either 10-75% RH or 5-95% RH, and the results of the second cycle should be used if there is significant weight loss at the end of the first cycle.

Hygroscopicity can be defined using various parameters. For purposes of the present invention, a non-hygroscopic molecule should not gain or lose more than 1.0%, or more preferably, 0.5% weight at 25 degrees C. when cycled between 10 and 75% RH (relative humidity at 25 degrees C.). The non-hygroscopic molecule more preferably should not gain or lose more than 1.0%, or more preferably, 0.5% weight when cycled between 5 and 95% RH at 25 degrees C., or more than 0.25% of its weight between 10 and 75% RH. Most preferably, a non-hygroscopic molecule will not gain or lose more than 0.25% of its weight when cycled between 5 and 95% RH.

Alternatively, for purposes of the present invention, hygroscopicity can be defined using the parameters of Callaghan et al., Equilibrium moisture content of pharmaceutical excipients, in Drug Dev. Ind. Pharm., Vol. 8, pp. 335-369 (1982). Callaghan et al. classified the degree of hygroscopicity into four classes.

Class 1: Non-hygroscopic Essentially no moisture increases occur at relative humidities below 90%.

Class 2: Slightly hygroscopic Essentially no moisture increases occur at relative humidities below 80%.

Class 3: Moderately hygroscopic Moisture content does not increase more than 5% after storage for 1 week at relative humidities below 60%.

Class 4: Very hygroscopic Moisture content increase may occur at relative humidities as low as 40 to 50%.

Alternatively, for purposes of the present invention, hygroscopicity can be defined using the parameters of the European Pharmacopoeia Technical Guide (1999, p. 86) which has defined hygrospocity, based on the static method, after storage at 25 degrees C. for 24 h at 80% RH:

Slightly hygroscopic: Increase in mass is less than 2 percent m/m and equal to or greater than 0.2 percent m/m.

Hygroscopic: Increase in mass is less than 15 percent m/m and equal to or greater than 0.2 percent m/m.

Very hygroscopic: Increase in mass is equal to or greater than 15 percent m/m.

Deliquescent: Sufficient water is absorbed to form a liquid.

PG solvates of the present invention can be set forth as being in Class 1, Class 2, or Class 3, or as being Slightly hygroscopic, Hygroscopic, or Very hygroscopic. PG solvates of the present invention can also be set forth based on their ability to reduce hygroscopicity. Thus, preferred PG solvates of the present invention are less hygroscopic than the non-PG solvated reference compound, e.g., the reference compound of a celecoxib sodium salt PG solvate is celecoxib sodium salt. Further included in the present invention are PG solvates that do not gain or lose more than 1.0% weight at 25 degrees C. when cycled between 10 and 75% RH, wherein the reference compound gains or loses more than 1.0% weight under the same conditions. Further included in the present invention are PG solvates that do not gain or lose more than 0.5% weight at 25 degrees C. when cycled between 10 and 75% RH, wherein the reference compound gains or loses more than 0.5% or more than 1.0% weight under the same conditions. Further included in the present invention are PG solvates that do not gain or lose more than 1.0% weight at 25 degrees C. when cycled between 5 and 95% RH, wherein the reference compound gains or loses more than 1.0% weight under the same conditions. Further included in the present invention are PG solvates that do not gain or lose more than 0.5% weight at 25 degrees C. when cycled between 5 and 95% RH, wherein the reference compound gains or loses more than 0.5% or more than 1.0% weight under the same conditions. Further included in the present invention are PG solvates that do not gain or lose more than 0.25% weight at 25 degrees C. when cycled between 5 and 95% RH, wherein the reference compound gains or loses more than 0.5% or more than 1.0% weight under the same conditions.

Further included in the present invention are PG solvates that have a hygroscopicity (according to Callaghan et al.) that is at least one class lower than the reference compound or at least two classes lower than the reference compound. Non-limiting examples include; a Class 1 PG solvate of a Class 2 reference compound, a Class 2 PG solvate of a Class 3 reference compound, a Class 3 PG solvate of a Class 4 reference compound, a Class 1 PG solvate of a Class 3 reference compound, a Class 1 PG solvate of a Class 4 reference compound, or a Class 2 PG solvate of a Class 4 reference compound.

Further included in the present invention are PG solvates that have a hygroscopicity (according to the European Pharmacopoeia Technical Guide) that is at least one class lower than the reference compound or at least two classes lower than the reference compound. Non-limiting examples include; a Slightly hygroscopic PG solvate of a Hygroscopic reference compound, a Hygroscopic PG solvate of a Very Hygroscopic reference compound, a Very Hygroscopic PG solvate of a Deliquescent reference compound, a Slightly hygroscopic PG solvate of a Very Hygroscopic reference compound, a Slightly hygroscopic PG solvate of a Deliquescent reference compound, a Hygroscopic PG solvate of a Deliquescent reference compound.

In another aspect of the present invention, the dissolution profile of the API (active pharmaceutical ingredient) (e.g. celecoxib) is modulated whereby the aqueous dissolution rate or the dissolution rate in simulated gastric fluid (SGF) or in simulated intestinal fluid (SIF), or in a solvent or plurality of solvents is increased. Dissolution rate is the rate at which API solids dissolve in a dissolution medium. For APIs whose absorption rates are faster than the dissolution rates (e.g., steroids), the rate-limiting step in the absorption process is often the dissolution rate. Because of a limited residence time at the absorption site, APIs that are not dissolved before they are removed from the intestinal absorption site are considered useless. Therefore, the rate of dissolution has a major impact on the performance of APIs that are poorly soluble. Because of this factor, the dissolution rate of APIs in solid dosage forms is an important, routine, quality control parameter used in the API manufacturing process.

Dissolution rate=KS(C _(s) −C)  (1)

where K is dissolution rate constant, S is the surface area, C_(s) is the apparent solubility, and C is the concentration of API in the dissolution media. For rapid API absorption, C_(s)−C is approximately equal to C_(s). The dissolution rate of APIs may be measured by conventional means known in the art.

The increase in the dissolution rate of a composition of the present invention, as compared to the unsolvated form, may be specified, such as by 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%, or by 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 500, 1000, 10,000, or 100,000 fold greater than the unsolvated form in the same solution. Conditions under which the dissolution rate is measured are discussed above. The increase in dissolution may be further specified by the time the composition remains supersaturated. Examples of above embodiments include: compositions with a dissolution rate, at 37 degrees C. and a pH of 7.0, that is increased at least 5 fold over the unsolvated form, compositions with a dissolution rate in SGF that is increased at least 5 fold over the unsolvated form, compositions with a dissolution rate in SIF that is increased at least 5 fold over the unsolvated form.

The present invention demonstrates that the length of time in which celecoxib or other APIs remains in solution can be increased to a surprising high degree by using a PG solvate form as discussed herein. The presence of propylene glycol allows the formation of a supersaturated solution of the API and a high concentration of API will remain in solution for an extended period of time. Celecoxib, for example, has a solubility in water of less than 1 microgram/mL and cannot be maintained as a supersaturated solution for any appreciable time. The present invention has drawn compositions that can be maintained for a period of time (e.g., 15, 30, 45, 60, minutes and longer) as supersaturated solutions at concentrations 2, 3, 5, 7, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%, or by 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 40, 50, 75, 100, 125, 150, 175, 200, 250, 300, 350, 400, 500, 1000, 10,000, or 100,000 fold greater than the solubility of the unsolvated form in the same solution (e.g., water or SGF).

The methods of the present invention can be used to make a pharmaceutical API formulation with greater solubility, dissolution, bioavailability, AUC, reduced time to T_(max), the average time from administration to reach peak blood serum levels, higher C_(max,), the average maximum blood serum concentration of API following administration, and longer T_(1/2), the average terminal half-life of API blood serum concentration following T_(max), when compared to the unsolvated form.

AUC is the area under the plot of plasma concentration of API (not logarithm of the concentration) against time after API administration. The area is conveniently determined by the “trapezoidal rule”: the data points are connected by straight line segments, perpendiculars are erected from the abscissa to each data point, and the sum of the areas of the triangles and trapezoids so constructed is computed. When the last measured concentration (C_(n), at time t_(n)) is not zero, the AUC from t_(n) to infinite time is estimated by C_(n)/k_(el).

The AUC is of particular use in estimating bioavailability of drugs, and in estimating total clearance of drugs (Cl_(T)). Following single intravenous doses, AUC=D/Cl_(T), where D is the dose, for single compartment systems obeying first-order elimination kinetics; alternatively, AUC=C₀/k_(el), where k_(el) is the drug elimination rate constant. With routes other than the intravenous AUC=F·D/Cl_(T), where F is the bioavailability of the drug.

Thus, in a further aspect, the present invention provides a process for modulating the bioavailability of an API when administered in its normal and effective dose range, whereby the AUC is increased, the time to T_(max) is reduced, or C_(max) is increased, which process comprises the preparation of a PG solvate.

Examples of the above embodiments include: compositions with a time to T_(max) that is reduced by at least 10% as compared to the neutral free form, compositions with a time to T_(max) that is reduced by at least 20% over the free form, compositions with a time to T_(max) that is reduced by at least 40% over the free form, compositions with a time to T_(max) that is reduced by at least 50% over the free form, compositions with a T_(max) that is reduced by at least 60% over the free form, compositions with a T_(max) that is reduced by at least 70% over the free form, compositions with a T_(max) that is reduced by at least 80% over the free form, compositions with a C_(max) that is increased by at least 20% over the free form, compositions with a C_(max) that is increased by at least 30% over the free form, compositions with a C_(max) that is increased by at least 40% over the free form, compositions with a C_(max) that is increased by at least 50% over the free form, compositions with a C_(max) that is increased by at least 60% over the free form, compositions with a C_(max) that is increased by at least 70% over the free form, compositions with a C_(max) that is increased by at least 80% over the free form,

compositions with a C_(max) that is increased by at least 2 times the free form, compositions with a C_(max) that is increased by at least 3 times the free form, compositions with a C_(max) that is increased by at least 4 times the free form, compositions with a C_(max) that is increased by at least 5 times the free form, compositions with a C_(max) that is increased by at least 6 times the free form, compositions with a C_(max) that is increased by at least 7 times the free form, compositions with a C_(max) that is increased by at least 8 times the free form, compositions with a C_(max) that is increased by at least 9 times the free form, compositions with a C_(max) that is increased by at least 10 times the free form, compositions with an AUC that is increased by at least 10% over the free form, compositions with an AUC that is increased by at least 20% over the free form, compositions with an AUC that is increased by at least 30% over the free form, compositions with an AUC that is increased by at least 40% over the free form, compositions with an AUC that is increased by at least 50% over the free form, compositions with an AUC that is increased by at least 60% over the free form, compositions with an AUC that is increased by at least 70% over the free form, compositions with an AUC that is increased by at least 80% over the free form, compositions with an AUC that is increased by at least 1 times the free form, compositions with an AUC that is increased by at least 2 times the free form, compositions with an AUC that is increased by at least 3 times the free form, or compositions with an AUC that is increased by at least 4 times the free form.

The uptake of a drug by a subject can also be assessed in terms of maximum blood serum concentration and time to reach maximum blood serum concentration. Pharmaceutical compositions with a more rapid onset to therapeutic effect typically reach a higher maximum blood serum concentration (C_(max)) a shorter time after oral administration (T_(max)). Preferably, compositions of the present invention have a higher C_(max) and/or a shorter T_(max) than in the unsolvated form. The T_(max) for the compositions of the present invention occurs within about 60 minutes, 55 minutes, 50 minutes, 45 minutes, 40 minutes, 35 minutes, 30 minutes, 25 minutes, 20 minutes, 15 minutes, 10 minutes, or within about 5 minutes of administration (e.g., oral administration). Even more preferably, the therapeutic effects of compositions of the present invention begin to occur within about 60 minutes, 55 minutes, 50 minutes, 45 minutes, 40 minutes, 35 minutes, 30 minutes, within about 25 minutes, within about 20 minutes, within about 15 minutes, within about 10 minutes, or within about 5 minutes of administration (e.g., oral administration).

Compositions of the present invention have a bioavailability greater than their respective unsolvated forms. In other embodiments, the compositions of the present invention have a bioavailability of at least 50%, 60%, 65%, 70%, 75%, 80%, 85%, 87%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%.

In a particular embodiment of the present invention, administration of celecoxib PG solvate to a subject may result in effective pain relief. Pain relief can be attained by inter alia reaching an appropriate blood serum concentration of a suitable analgesic. In the case of the selective COX-2 inhibitor celecoxib, about 250 ng/mL is an appropriate concentration for the relief of pain of various causes. Any standard pharmacokinetic protocol can be used to determine blood serum concentration profile in humans following oral administration of a celecoxib formulation, and thereby establish whether that formulation meets the pharmacokinetic criteria set out herein. The prior art includes many examples of pharmacokinetic studies and as such U.S. Pat. No. 6,579,895 and WO 01/91750 are hereby included as references in their entirety.

In a further aspect the present invention provides a process for improving the dose response of an API by making a composition of the present invention. Dose response is the quantitative relationship between the magnitude of response and the dose inducing the response and may be measured by conventional means known in the art. The curve relating therapeutic effect (as the dependent variable) to dose (as the independent variable) for an API-cell system is the “dose-response curve”. Typically, the dose-response curve is the measured response to an API plotted against the dose of the API (mg/kg) given. The dose response curve can also be a curve of AUC against the dose of the API given.

The dose-response curve for many APIs (e.g. presently-marketed celecoxib (CELEBREX™)) is nonlinear. Preferably, the dose-response curves for the PG solvate compositions of the present invention are linear or contain a larger linear region than presently-marketed celecoxib. A preferred embodiment of the present invention may incorporate a dose-response curve with a linear slope that is steeper than that of celecoxib. This would allow a faster-onset of therapeutic relief from a smaller dosage of API. An initially steep dose-response curve which gradually levels out could be employed to generate a controlled-release formulation. Also, the absorption or uptake of many APIs (e.g. presently-marketed celecoxib) depends in part on food effects, such that uptake of the API increases when taken with food, especially fatty food. Preferably, uptake of the PG solvates of the present invention exhibit a decreased dependence on food, such that the difference in uptake of the PG solvates when taken with food and when not taken with food is less than the difference in uptake of the unsolvated form.

The compositions of the present invention, including the active pharmaceutical ingredient (API) and formulations comprising the API, are suitably stable for pharmaceutical use. Preferably, the API or formulations thereof of the present invention are stable such that when stored at 30 degrees C. for 2 years, less than 0.2% of any one degradant is formed. The term degradant refers herein to product(s) of a single type of chemical reaction. For example, if a hydrolysis event occurs that cleaves a molecule into two products, for the purpose of the present invention, it would be considered a single degradant. More preferably, when stored at 40 degrees C. for 2 years, less than 0.2% of any one degradant is formed. Alternatively, when stored at 30 degrees C. for 3 months, less than 0.2% or 0.15%, or 0.1% of any one degradant is formed, or when stored at 40 degrees C. for 3 months, less than 0.2% or 0.15%, or 0.1% of any one degradant is formed. Further alternatively, when stored at 60 degrees C. for 4 weeks, less than 0.2% or 0.15%, or 0.1% of any one degradant is formed. The relative humidity (RH) may be specified as ambient (RH), 75% (RH), or as any single integer between 1 to 99%.

APIs prepared in the form of propylene glycol solvates have several important advantages over other solvates and their free form counterparts. In general, solvates are more commonly formed with water, methanol, ethanol, or other alcohols than with propylene glycol. These more common solvates are more easily removed from the crystal matrix by elevated temperatures than propylene glycol. PG solvates have an increased thermal stability over those of more traditional solvates. Also, PG solvates are generally more pharmaceutically acceptable than other common solvates, including those formed from alcohols other than ethanol. Investigations of the PG solvates of the present invention have shown fewer solvation states than hydration states. Reference compounds for PG solvates can be unsolvated free acid, unsolvated free base, zwitter ions, hydrates, or other solvates (e.g. methanol, ethanol, etc.). This decrease in form diversity associated with PG solvates can lead to more predictability and more consistent results during production and quality control. Stabilization of a desired solvate or polymorph can be achieved by causing the less desirable forms (e.g. solvates, polymorphs, hydrates) to be energetically less favorable than the desired form. In this way, PG solvates can aid in the production of pharmaceutical formulations with increased form stability.

The present invention further relates to methods of making a pharmaceutical solvate more stable at elevated temperatures (e.g. 30, 40, 50 degrees C.) by producing a PG solvate of the drug. The present invention further relates to methods of making a more pharmaceutically acceptable solvate of many APIs by employing propylene glycol rather than more biologically harmful solvents (e.g. methanol). The present invention further relates to methods of reducing the number of forms (e.g. hydration states, solvation states, polymorphs, etc.) possible for a pharmaceutical solvate.

Pharmaceutically acceptable PG solvates can be administered by controlled- or delayed-release means. Controlled-release pharmaceutical products have a common goal of improving drug therapy over that achieved by their non-controlled release counterparts. Ideally, the use of an optimally designed controlled-release preparation in medical treatment is characterized by a minimum of drug substance being employed to cure or control the condition in a minimum amount of time. Advantages of controlled-release formulations include: 1) extended activity of the drug; 2) reduced dosage frequency; 3) increased patient compliance; 4) usage of less total drug; 5) reduction in local or systemic side effects; 6) minimization of drug accumulation; 7) reduction in blood level fluctuations; 8) improvement in efficacy of treatment; 9) reduction of potentiation or loss of drug activity; and 10) improvement in speed of control of diseases or conditions. (Kim, Cherng-ju, Controlled Release Dosage Form Design, Technomic Publishing, Lancaster, Pa.: 2000).

Conventional dosage forms generally provide rapid or immediate drug release from the formulation. Depending on the pharmacology and pharmacokinetics of the drug, use of conventional dosage forms can lead to wide fluctuations in the concentrations of the drug in a patient's blood and other tissues. These fluctuations can impact a number of parameters, such as dose frequency, onset of action, duration of efficacy, maintenance of therapeutic blood levels, toxicity, side effects, and the like. Advantageously, controlled-release formulations can be used to control a drug's onset of action, duration of action, plasma levels within the therapeutic window, and peak blood levels. In particular, controlled- or extended-release dosage forms or formulations can be used to ensure that the maximum effectiveness of a drug is achieved while minimizing potential adverse effects and safety concerns, which can occur both from under dosing a drug (i.e., going below the minimum therapeutic levels) as well as exceeding the toxicity level for the drug.

Most controlled-release formulations are designed to initially release an amount of drug (active ingredient) that promptly produces the desired therapeutic effect, and gradually and continually release other amounts of drug to maintain this level of therapeutic or prophylactic effect over an extended period of time. In order to maintain this constant level of drug in the body, the drug must be released from the dosage form at a rate that will replace the amount of drug being metabolized and excreted from the body. Controlled-release of an active ingredient can be stimulated by various conditions including, but not limited to, pH, ionic strength, osmotic pressure, temperature, enzymes, water, and other physiological conditions or compounds.

A variety of known controlled- or extended-release dosage forms, formulations, and devices can be adapted for use with the PG solvates of the present invention. Examples include, but are not limited to, those described in U.S. Pat. Nos. 3,845,770; 3,916,899; 3,536,809; 3,598,123; 4,008,719; 5,674,533; 5,059,595; 5,591,767; 5,120,548; 5,073,543; 5,639,476; 5,354,556; 5,733,566; and 6,365,185 B1; each of which is incorporated herein by reference.

These dosage forms can be used to provide slow or controlled-release of one or more active ingredients using, for example, hydroxypropylmethyl cellulose, other polymer matrices, gels, permeable membranes, osmotic systems (such as OROS® (Alza Corporation, Mountain View, Calif. USA)), multilayer coatings, microparticles, liposomes, or microspheres or a combination thereof to provide the desired release profile in varying proportions. Additionally, ion exchange materials can be used to prepare immobilized, adsorbed salt forms and thus effect controlled delivery of the drug. Examples of specific anion exchangers include, but are not limited to, Duolite® A568 and Duolite® AP143 (Rohm & Haas, Spring House, Pa. USA).

One embodiment of the invention encompasses a unit dosage form which comprises a pharmaceutically acceptable PG solvate, or a polymorph, solvate, hydrate, dehydrate, co-crystal, anhydrous, or amorphous form thereof, and one or more pharmaceutically acceptable excipients or diluents, wherein the pharmaceutical composition or dosage form is formulated for controlled-release. Specific dosage forms utilize an osmotic drug delivery system.

A particular and well-known osmotic drug delivery system is referred to as OROS® (Alza Corporation, Mountain View, Calif. USA). This technology can readily be adapted for the delivery of compounds and compositions of the invention. Various aspects of the technology are disclosed in U.S. Pat. Nos. 6,375,978 B1; 6,368,626 B1; 6,342,249 B1; 6,333,050 B2; 6,287,295 B1; 6,283,953 B1; 6,270,787 B1; 6,245,357 B1; and 6,132,420; each of which is incorporated herein by reference. Specific adaptations of OROS® that can be used to administer compounds and compositions of the invention include, but are not limited to, the OROS® Push-Pull™, Delayed Push-Pull™, Multi-Layer Push-Pull™, and Push-Stick™ Systems, all of which are well known. See, e.g., http://www.alza.com. Additional OROS® systems that can be used for the controlled oral delivery of compounds and compositions of the invention include OROS®-CT and L-OROS®. Id.; see also, Delivery Times, vol. II, issue II (Alza Corporation).

Conventional OROS® oral dosage forms are made by compressing a drug powder (e.g., celecoxib sodium PG solvate) into a hard tablet, coating the tablet with cellulose derivatives to form a semi-permeable membrane, and then drilling an orifice in the coating (e.g., with a laser). (Kim, Cherng-ju, Controlled Release Dosage Form Design, Technomic Publishing, Lancaster, Pa.: 2000). The advantage of such dosage forms is that the delivery rate of the drug is not influenced by physiological or experimental conditions. Even a drug with a pH-dependent solubility can be delivered at a constant rate regardless of the pH of the delivery medium. But because these advantages are provided by a build-up of osmotic pressure within the dosage form after administration, conventional OROS® drug delivery systems cannot be used to effectively deliver drugs with low water solubility. Because PG solvates and complexes of this invention (e.g., celecoxib sodium PG solvate) are far more soluble in water than unsolvated forms, they are well suited for osmotic-based delivery to patients.

A specific dosage form of the invention comprises: a wall defining a cavity, the wall having an exit orifice formed or formable therein and at least a portion of the wall being semipermeable; an expandable layer located within the cavity remote from the exit orifice and in fluid communication with the semipermeable portion of the wall; a dry or substantially dry state drug layer located within the cavity adjacent to the exit orifice and in direct or indirect contacting relationship with the expandable layer; and a flow-promoting layer interposed between the inner surface of the wall and at least the external surface of the drug layer located within the cavity, wherein the drug layer comprises a PG solvate, or a polymorph, solvate, hydrate, dehydrate, co-crystal, anhydrous, or amorphous form thereof. See U.S. Pat. No. 6,368,626, the entirety of which is incorporated herein by reference.

Another specific dosage form of the invention comprises: a wall defining a cavity, the wall having an exit orifice formed or formable therein and at least a portion of the wall being semipermeable; an expandable layer located within the cavity remote from the exit orifice and in fluid communication with the semipermeable portion of the wall; a drug layer located within the cavity adjacent the exit orifice and in direct or indirect contacting relationship with the expandable layer; the drug layer comprising a liquid, active agent formulation absorbed in porous particles, the porous particles being adapted to resist compaction forces sufficient to form a compacted drug layer without significant exudation of the liquid, active agent formulation, the dosage form optionally having a placebo layer between the exit orifice and the drug layer, wherein the active agent formulation comprises a PG solvate, or a polymorph, solvate, hydrate, dehydrate, co-crystal, anhydrous, or amorphous form thereof. See U.S. Pat. No. 6,342,249, the entirety of which is incorporated herein by reference.

Excipients employed in pharmaceutical compositions of the present invention can be solids, semi-solids, liquids or combinations thereof. Compositions of the invention containing excipients can be prepared by any known technique of pharmacy that comprises admixing an excipient with a drug or therapeutic agent. A pharmaceutical composition of the invention contains a desired amount of API per dose unit and, if intended for oral administration, can be in the form, for example, of a tablet, a caplet, a pill, a hard or soft capsule, a lozenge, a cachet, a dispensable powder, granules, a suspension, an elixir, a dispersion, a liquid, or any other form reasonably adapted for such administration. Presently preferred are oral dosage forms that are discrete dose units each containing a predetermined amount of the drug, such as tablets or capsules.

Non-limiting examples follow of excipients that can be used to prepare pharmaceutical compositions of the invention.

Pharmaceutical compositions of the invention optionally comprise one or more pharmaceutically acceptable carriers or diluents as excipients. Suitable carriers or diluents illustratively include, but are not limited to, either individually or in combination, lactose, including anhydrous lactose and lactose monohydrate; starches, including directly compressible starch and hydrolyzed starches (e.g., Celutab™ and Emdex™); mannitol; sorbitol; xylitol; dextrose (e.g., Cerelose™ 2000) and dextrose monohydrate; dibasic calcium phosphate dihydrate; sucrose-based diluents; confectioner's sugar; monobasic calcium sulfate monohydrate; calcium sulfate dihydrate; granular calcium lactate trihydrate; dextrates; inositol; hydrolyzed cereal solids; amylose; celluloses including microcrystalline cellulose, food grade sources of alpha- and amorphous cellulose (e.g., RexcelJ), powdered cellulose, hydroxypropylcellulose (HPC) and hydroxypropylmethylcellulose (HPMC); calcium carbonate; glycine; bentonite; block co-polymers; polyvinylpyrrolidone; and the like. Such carriers or diluents, if present, constitute in total about 5% to about 99%, preferably about 10% to about 85%, and more preferably about 20% to about 80%, of the total weight of the composition. The carrier, carriers, diluent, or diluents selected preferably exhibit suitable flow properties and, where tablets are desired, compressibility.

Lactose, mannitol, dibasic sodium phosphate, and microcrystalline cellulose (particularly Avicel PH microcrystalline cellulose such as Avicel PH 101), either individually or in combination, are preferred diluents. These diluents are chemically compatible with celecoxib. The use of extragranular microcrystalline cellulose (that is, microcrystalline cellulose added to a granulated composition) can be used to improve hardness (for tablets) and/or disintegration time. Lactose, especially lactose monohydrate, is particularly preferred. Lactose typically provides compositions having suitable release rates of celecoxib, stability, pre-compression flowability, and/or drying properties at a relatively low diluent cost. It provides a high density substrate that aids densification during granulation (where wet granulation is employed) and therefore improves blend flow properties and tablet properties.

Pharmaceutical compositions of the invention optionally comprise one or more pharmaceutically acceptable disintegrants as excipients, particularly for tablet formulations. Suitable disintegrants include, but are not limited to, either individually or in combination, starches, including sodium starch glycolate (e.g., Explotab™ of PenWest) and pregelatinized corn starches (e.g., National™ 1551 of National Starch and Chemical Company, National™ 1550, and Colorcon™ 1500), clays (e.g., Veegum™ HV of R.T. Vanderbilt), celluloses such as purified cellulose, microcrystalline cellulose, methylcellulose, carboxymethylcellulose and sodium carboxymethylcellulose, croscarmellose sodium (e.g., Ac-Di-Sol™ of FMC), alginates, crospovidone, and gums such as agar, guar, locust bean, karaya, pectin and tragacanth gums.

Disintegrants may be added at any suitable step during the preparation of the composition, particularly prior to granulation or during a lubrication step prior to compression. Such disintegrants, if present, constitute in total about 0.2% to about 30%, preferably about 0.2% to about 10%, and more preferably about 0.2% to about 5%, of the total weight of the composition.

Croscarmellose sodium is a preferred disintegrant for tablet or capsule disintegration, and, if present, preferably constitutes about 0.2% to about 10%, more preferably about 0.2% to about 7%, and still more preferably about 0.2% to about 5%, of the total weight of the composition. Croscarmellose sodium confers superior intragranular disintegration capabilities to granulated pharmaceutical compositions of the present invention.

Pharmaceutical compositions of the invention optionally comprise one or more pharmaceutically acceptable binding agents or adhesives as excipients, particularly for tablet formulations. Such binding agents and adhesives preferably impart sufficient cohesion to the powder being tableted to allow for normal processing operations such as sizing, lubrication, compression and packaging, but still allow the tablet to disintegrate and the composition to be absorbed upon ingestion. Such binding agents may also prevent or inhibit crystallization or recrystallization of a celecoxib salt of the present invention once the salt has been dissolved in a solution. Suitable binding agents and adhesives include, but are not limited to, either individually or in combination, acacia; tragacanth; sucrose; gelatin; glucose; starches such as, but not limited to, pregelatinized starches (e.g., National™ 1511 and National™ 1500); celluloses such as, but not limited to, methylcellulose and carmellose sodium (e.g., Tylose™); alginic acid and salts of alginic acid; magnesium aluminum silicate; PEG; guar gum; polysaccharide acids; bentonites; povidone, for example povidone K-15, K-30 and K-29/32; polymethacrylates; HPMC; hydroxypropylcellulose (e.g., Klucel™ of Aqualon); and ethylcellulose (e.g., Ethocel™ of the Dow Chemical Company). Such binding agents and/or adhesives, if present, constitute in total about 0.5% to about 25%, preferably about 0.75% to about 15%, and more preferably about 1% to about 10%, of the total weight of the pharmaceutical composition.

Many of the binding agents are polymers comprising amide, ester, ether, alcohol or ketone groups and, as such, are preferably included in pharmaceutical compositions of the present invention. Polyvinylpyrrolidones such as povidone K-30 are especially preferred. Polymeric binding agents can have varying molecular weight, degrees of crosslinking, and grades of polymer. Polymeric binding agents can also be copolymers, such as block co-polymers that contain mixtures of ethylene oxide and propylene oxide units. Variation in these units' ratios in a given polymer affects properties and performance. Examples of block co-polymers with varying compositions of block units are Poloxamer 188 and Poloxamer 237 (BASF Corporation).

Pharmaceutical compositions of the invention optionally comprise one or more pharmaceutically acceptable wetting agents as excipients. Non-limiting examples of surfactants that can be used as wetting agents in pharmaceutical compositions of the invention include quaternary ammonium compounds, for example benzalkonium chloride, benzethonium chloride and cetylpyridinium chloride, dioctyl sodium sulfosuccinate, polyoxyethylene alkylphenyl ethers, for example nonoxynol 9, nonoxynol 10, and octoxynol 9, poloxamers (polyoxyethylene and polyoxypropylene block copolymers), polyoxyethylene fatty acid glycerides and oils, for example polyoxyethylene (8) caprylic/capric mono- and diglycerides (e.g., Labrasol™ of Gattefosse), polyoxyethylene (35) castor oil and polyoxyethylene (40) hydrogenated castor oil; polyoxyethylene alkyl ethers, for example polyoxyethylene (20) cetostearyl ether, polyoxyethylene fatty acid esters, for example polyoxyethylene (40) stearate, polyoxyethylene sorbitan esters, for example polysorbate 20 and polysorbate 80 (e.g., Tween™ 80 of ICI), propylene glycol fatty acid esters, for example propylene glycol laurate (e.g., Lauroglycol™ of Gattefosse), sodium lauryl sulfate, fatty acids and salts thereof, for example oleic acid, sodium oleate and triethanolamine oleate, glyceryl fatty acid esters, for example glyceryl monostearate, sorbitan esters, for example sorbitan monolaurate, sorbitan monooleate, sorbitan monopalmitate and sorbitan monostearate, tyloxapol, and mixtures thereof. Such wetting agents, if present, constitute in total about 0.25% to about 15%, preferably about 0.4% to about 10%, and more preferably about 0.5% to about 5%, of the total weight of the pharmaceutical composition.

Wetting agents that are anionic surfactants are preferred. Sodium lauryl sulfate is a particularly preferred wetting agent. Sodium lauryl sulfate, if present, constitutes about 0.25% to about 7%, more preferably about 0.4% to about 4%, and still more preferably about 0.5% to about 2%, of the total weight of the pharmaceutical composition.

Pharmaceutical compositions of the invention optionally comprise one or more pharmaceutically acceptable lubricants (including anti-adherents and/or glidants) as excipients. Suitable lubricants include, but are not limited to, either individually or in combination, glyceryl behapate (e.g., Compritol™ 888 of Gattefosse); stearic acid and salts thereof, including magnesium, calcium and sodium stearates; hydrogenated vegetable oils (e.g., Sterotex™ of Abitec); colloidal silica; talc; waxes; boric acid; sodium benzoate; sodium acetate; sodium fumarate; sodium chloride; DL-leucine; PEG (e.g., Carbowax™ 4000 and Carbowax™ 6000 of the Dow Chemical Company); sodium oleate; sodium lauryl sulfate; and magnesium lauryl sulfate. Such lubricants, if present, constitute in total about 0.1% to about 10%, preferably about 0.2% to about 8%, and more preferably about 0.25% to about 5%, of the total weight of the pharmaceutical composition.

Magnesium stearate is a preferred lubricant used, for example, to reduce friction between the equipment and granulated mixture during compression of tablet formulations.

Suitable anti-adherents include, but are not limited to, talc, cornstarch, DL-leucine, sodium lauryl sulfate and metallic stearates. Talc is a preferred anti-adherent or glidant used, for example, to reduce formulation sticking to equipment surfaces and also to reduce static in the blend. Talc, if present, constitutes about 0.1% to about 10%, more preferably about 0.25% to about 5%, and still more preferably about 0.5% to about 2%, of the total weight of the pharmaceutical composition.

Glidants can be used to promote powder flow of a solid formulation. Suitable glidants include, but are not limited to, colloidal silicon dioxide, starch, talc, tribasic calcium phosphate, powdered cellulose and magnesium trisilicate. Colloidal silicon dioxide is particularly preferred.

Other excipients such as colorants, flavors and sweeteners are known in the pharmaceutical art and can be used in pharmaceutical compositions of the present invention. Tablets can be coated, for example with an enteric coating, or uncoated. Compositions of the invention can further comprise, for example, buffering agents.

Optionally, one or more effervescent agents can be used as disintegrants and/or to enhance organoleptic properties of pharmaceutical compositions of the invention. When present in pharmaceutical compositions of the invention to promote dosage form disintegration, one or more effervescent agents are preferably present in a total amount of about 30% to about 75%, and preferably about 45% to about 70%, for example about 60%, by weight of the pharmaceutical composition.

According to a particularly preferred embodiment of the invention, an effervescent agent, present in a solid dosage form in an amount less than that effective to promote disintegration of the dosage form, provides improved dispersion of the celecoxib in an aqueous medium. Without being bound by theory, it is believed that the effervescent agent is effective to accelerate dispersion of the drug, such as celecoxib, from the dosage form in the gastrointestinal tract, thereby further enhancing absorption and rapid onset of therapeutic effect. When present in a pharmaceutical composition of the invention to promote intragastrointestinal dispersion but not to enhance disintegration, an effervescent agent is preferably present in an amount of about 1% to about 20%, more preferably about 2.5% to about 15%, and still more preferably about 5% to about 10%, by weight of the pharmaceutical composition.

An “effervescent agent” herein is an agent comprising one or more compounds which, acting together or individually, evolve a gas on contact with water. The gas evolved is generally oxygen or, most commonly, carbon dioxide. Preferred effervescent agents comprise an acid and a base that react in the presence of water to generate carbon dioxide gas. Preferably, the base comprises an alkali metal or alkaline earth metal carbonate or bicarbonate and the acid comprises an aliphatic carboxylic acid.

Non-limiting examples of suitable bases as components of effervescent agents useful in the invention include carbonate salts (e.g., calcium carbonate), bicarbonate salts (e.g., sodium bicarbonate), sesquicarbonate salts, and mixtures thereof. Calcium carbonate is a preferred base.

Non-limiting examples of suitable acids as components of effervescent agents and/or solid organic acids useful in the invention include citric acid, tartaric acid (as D-, L-, or D/L-tartaric acid), malic acid, maleic acid, fumaric acid, adipic acid, succinic acid, acid anhydrides of such acids, acid salts of such acids, and mixtures thereof. Citric acid is a preferred acid.

In a preferred embodiment of the invention, where the effervescent agent comprises an acid and a base, the weight ratio of the acid to the base is about 1:100 to about 100:1, more preferably about 1:50 to about 50:1, and still more preferably about 1:10 to about 10:1. In a further preferred embodiment of the invention, where the effervescent agent comprises an acid and a base, the ratio of the acid to the base is approximately stoichiometric.

Excipients which solubilize metal salts of drugs like celecoxib typically have both hydrophilic and hydrophobic regions, or are preferably amphiphilic or have amphiphilic regions. One type of amphiphilic or partially-amphiphilic excipient comprises an amphiphilic polymer or is an amphiphilic polymer. A specific amphiphilic polymer is a polyalkylene glycol, which is commonly comprised of ethylene glycol and/or propylene glycol subunits. Such polyalkylene glycols can be esterified at their termini by a carboxylic acid, ester, acid anhyride or other suitable moiety. Examples of such excipients include poloxamers (symmetric block copolymers of ethylene glycol and propylene glycol; e.g., poloxamer 237), polyalkyene glycolated esters of tocopherol (including esters formed from a di- or multi-functional carboxylic acid; e.g., d-alpha-tocopherol polyethylene glycol-1000 succinate), and macrogolglycerides (formed by alcoholysis of an oil and esterification of a polyalkylene glycol to produce a mixture of mono-, di- and tri-glycerides and mono- and di-esters; e.g., stearoyl macrogol-32 glycerides). Such pharmaceutical compositions are advantageously administered orally.

Solid dosage forms of the invention can be prepared by any suitable process, not limited to processes described herein.

An illustrative process comprises (a) a step of blending a celecoxib salt of the invention with one or more excipients to form a blend, and (b) a step of tableting or encapsulating the blend to form tablets or capsules, respectively.

In a preferred process, solid dosage forms are prepared by a process comprising (a) a step of blending a drug salt such as a celecoxib salt of the invention with one or more excipients to form a blend, (b) a step of granulating the blend to form a granulate, and (c) a step of tableting or encapsulating the blend to form tablets or capsules respectively. Step (b) can be accomplished by any dry or wet granulation technique known in the art, but is preferably a dry granulation step. A salt of the present invention is advantageously granulated to form particles of about 1 micrometer to about 100 micrometer, about 5 micrometer to about 50 micrometer, or about 10 micrometer to about 25 micrometer. One or more diluents, one or more disintegrants and one or more binding agents are preferably added, for example in the blending step, a wetting agent can optionally be added, for example in the granulating step, and one or more disintegrants are preferably added after granulating but before tableting or encapsulating. A lubricant is preferably added before tableting. Blending and granulating can be performed independently under low or high shear. A process is preferably selected that forms a granulate that is uniform in drug content, that readily disintegrates, that flows with sufficient ease so that weight variation can be reliably controlled during capsule filling or tableting, and that is dense enough in bulk so that a batch can be processed in the selected equipment and individual doses fit into the specified capsules or tablet dies.

In an alternative embodiment, solid dosage forms are prepared by a process that includes a spray drying step, wherein a celecoxib salt is suspended with one or more excipients in one or more sprayable liquids, preferably a non-protic (e.g., non-aqueous or non-alcoholic) sprayable liquid, and then is rapidly spray dried over a current of warm air.

A granulate or spray dried powder resulting from any of the above illustrative processes can be compressed or molded to prepare tablets or encapsulated to prepare capsules.

Conventional tableting and encapsulation techniques known in the art can be employed. Where coated tablets are desired, conventional coating techniques are suitable.

Excipients for tablet compositions of the invention are preferably selected to provide a disintegration time of less than about 30 minutes, preferably about 25 minutes or less, more preferably about 20 minutes or less, and still more preferably about 15 minutes or less, in a standard disintegration assay.

Celecoxib dosage forms of the invention preferably comprise celecoxib in a daily dosage amount of about 10 mg to about 1000 mg, more preferably about 25 mg to about 400 mg, and most preferably about 50 mg to about 200 mg.

In a further embodiment the PG solvate comprises an API from Table 3. For APIs in Table 3 listed as salts, solvates, hydrates, and the like, the PG solvate can either be of the form listed in Table 3 or a PG solvate of the free form, or a PG solvate of another form that is not listed. Table 3 includes the CAS number, chemical name or a PCT or patent reference (each incorporated herein in their entireties). In another embodiment, any one or more of the APIs of Table 3 may be specifically excluded from the present invention. Any APIs currently known in the art may also be specifically excluded from the present invention. For example, azithromycin and cephalosporin may be specifically excluded from the present invention.

EXEMPLIFICATION Procedure for Raman Acquisition Acquisition

The sample was either left in the glass vial in which it was processed or an aliquot of the sample was transferred to a glass slide. The glass vial or slide was positioned in the sample chamber. The measurement was made using an Almega™ Dispersive Raman (Almega™ Dispersive Raman, Thermo-Nicolet, 5225 Verona Road, Madison, Wis. 53711-4495) system fitted with a 785 nm laser source. The sample was manually brought into focus using the microscope portion of the apparatus with a 10× power objective (unless otherwise noted), thus directing the laser onto the surface of the sample. The spectrum was acquired using the parameters outlined in Table 1. (Exposure times and number of exposures may vary; changes to parameters will be indicated for each acquisition.)

TABLE 2 Raman Spectral acquisition parameters Parameter Setting Used Exposure time (s) 2.0 Number of exposures 10 Laser source wavelength (nm) 785 Laser power (%) 100 Aperture shape pin hole Aperture size (um) 100 Spectral range 104-3428 Grating position Single Temperature at acquisition (degrees C.) 24.0

Procedure for Powder X-Ray Diffraction (PXRD)

All powder x-ray diffraction patterns were obtained using the D/Max Rapid X-ray Diffractometer (D/Max Rapid, Contact Rigaku/MSC, 9009 New Trails Drive, The Woodlands, Tex., USA 77381-5209) equipped with a copper source (Cu/K_(α) 1.5406{acute over (Å)}), manual x-y stage, and 0.3 mm collimator, unless otherwise indicated. The sample was loaded into a 0.3 mm boron rich glass capillary tube (e.g., Charles Supper Company, 15 Tech Circle, Natick Mass. 01760-1024) by sectioning off one end of the tube and tapping the open, sectioned end into a bed of the powdered sample or into the sediment of a slurried precipitate. Note, precipitate can be amorphous or crystalline. The loaded capillary was mounted in a holder that was secured into the x-y stage. A diffractogram was acquired (e.g., Control software: RINT Rapid Control Software, Rigaku Rapid/XRD, version 1.0.0, © 1999 Rigaku Co.) under ambient conditions at a power setting of 46 kV at 40 mA in reflection mode, while oscillating about the omega-axis from 0-5 degrees at 1 degree/s and spinning about the phi-axis at 2 degrees/s. The exposure time was 15 minutes unless otherwise specified. The diffractogram obtained was integrated over 2-theta from 2-60 degrees and chi (1 segment) from 0-360 degrees at a step size of 0.02 degrees using the cyllnt utility in the RINT Rapid display software (Analysis software: RINT Rapid display software, version 1.18, Rigaku/MSC.) provided by Rigaku with the instrument. The dark counts value was set to 8 as per the system calibration (System set-up and calibration by Rigaku); normalization was set to average; the omega offset was set to 180′; and no chi or phi offsets were used for the integration. The analysis software JADE XRD Pattern Processing, versions 5.0 and 6.0 ((⁸1995-2002, Materials Data, Inc. was also used.

The relative intensity of peaks in a diffractogram is not necessarily a limitation of the PXRD pattern because peak intensity can vary from sample to sample, e.g., due to crystalline impurities. Further, the angles of each peak can vary by about +/−0.1 degrees, preferably +/−0.05. The entire pattern or most of the pattern peaks may also shift by about +/−0.1 degree due to differences in calibration, settings, and other variations from instrument to instrument and from operator to operator. The above limitations result in a PXRD error of +/−0.1 degrees 2-theta for each diffraction peak.

Procedure for Differential Scanning Calorimetry (DSC)

An aliquot of the sample was weighed into an aluminum sample pan. (e.g., Pan part #900786.091; lid part #900779.901; TA Instruments, 109 Lukens Drive, New Castle, Del. 19720) The sample pan was sealed either by crimping for dry samples or press fitting for wet samples (e.g., hydrated or solvated samples). The sample pan was loaded in to the apparatus (DSC: Q1000 Differential Scanning Calorimeter, TA Instruments, 109 Lukens Drive, New Castle, Del. 19720), which is equipped with an autosampler, and a thermogram was obtained by individually heating the sample (e.g., Control software: Advantage for QW-Series, version 1.0.0.78, Thermal Advantage Release 2.0, © 2001 TA instruments—Water LLC) at a rate of 10 degrees C./min from T_(min) (typically 20 degrees C.) to T_(max) (typically 300 degrees C.) (Heating rate and temperature range may vary, changes to these parameters will be indicated for each sample) using an empty aluminum pan as a reference. Dry nitrogen (e.g., Compressed nitrogen, grade 4.8, BOC Gases, 575 Mountain Avenue, Murray Hill, N.J. 07974-2082) was used as a sample purge gas and was set at a flow rate of 50 mL/min. Thermal transitions were viewed and analyzed using the analysis software (Analysis Software: Universal Analysis 2000 for Windows 95/95/2000/NT, version 3.1E; Build 3.1.0.40, © 1991-2001TA instruments—Water LLC) provided with the instrument.

Procedure for Thermogravimetric Analysis (TGA)

An aliquot of the sample was transferred into a platinum sample pan. (Pan part #952019.906; TA Instruments, 109 Lukens Drive, New Castle, Del. 19720) The pan was placed on the loading platform and was then automatically loaded in to the apparatus (TGA: Q500 Thermogravimetric Analyzer, TA Instruments, 109 Lukens Drive, New Castle, Del. 19720) using the control software (Control software: Advantage for QW-Series, version 1.0.0.78, Thermal Advantage Release 2.0, © 2001 TA instruments—Water LLC). Thermograms were obtained by individually heating the sample at 10 degrees C./min from 25 degrees C. to 300 degrees C. (Heating rate and temperature range may vary, changes in parameters will be indicated for each sample) under flowing dry nitrogen (e.g., Compressed nitrogen, grade 4.8, BOC Gases, 575 Mountain Avenue, Murray Hill, N.J. 07974-2082), with a sample purge flow rate of 60 mL/min and a balance purge flow rate of 40 mL/min. Thermal transitions (e.g. weight changes) were viewed and analyzed using the analysis software (Analysis Software: Universal Analysis 2000 for Windows 95/95/2000/NT, version 3.1E; Build 3.1.0.40, © 1991-2001TA instruments—Water LLC) provided with the instrument.

Example 1 Celecoxib Sodium Salt PG Solvate

A propylene glycol solvate of the sodium salt of celecoxib was prepared. To a solution of celecoxib (312 mg; 0.818 mmol) in diethyl ether (6 mL) was added propylene glycol (0.127 mL, 1.73 mmol). To the clear solution was added sodium ethoxide in ethanol (21%, 0.275 mL, 0.817 mmol). After 1 minute, crystals began to form. After 5 minutes, the solid had completely crystallized. The solid was collected by filtration and was washed with additional diethyl ether (10 mL). The off-white solid was then air-dried and collected. The crystalline salt form was identified as a 1:1 solvate of propylene glycol. The solid was characterized by TGA and PXRD. The results are depicted in FIGS. 1 and 2A.

FIG. 1 shows the results of TGA. A weight loss of about 15.6% was observed between about 65 and 200 degrees C. which represents 1 molar equivalent of propylene glycol to celecoxib Na salt. FIG. 2A shows the results of PXRD. Peaks, in 2-theta angles, that can be used to characterize the solvate include any 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 of the following: 3.77, 7.57, 8.21, 11.33, 14.23, 16.13, 18.69, 20.65, 22.69 and 24.77 degrees or any one or any combination of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more peaks of FIG. 2A. The TGA thermogram or PXRD diffractogram data may be used alone or in any combination to characterize the solvate. A 0.8 mm collimator was used during acquisition of the diffractogram.

Several closely related, yet distinguishable, PXRD diffractograms have been obtained by performing the above synthesis several times. FIGS. 2B, 2C, and 2D are additional diffractograms of the propylene glycol solvate of celecoxib sodium salt. A comparison of these diffractograms yields a number of noticeable differences. For example, the peak at 8.21 degrees 2-theta in FIG. 2A is not present in FIG. 2B or 2C. Another peak at 8.79 degrees 2-theta, present in FIGS. 2B and 2D, is not found in FIG. 2A or 2C. Other distinctions can also be found between the four diffractograms. Such distinctions in otherwise similar diffractograms suggest the existence of polymorphism or perhaps a variable hydrate.

In another embodiment of the present invention, a PG solvate of an API can give rise to distinct PXRD diffractograms. This can be caused by polymorphism, a variable hydrate, a different environmental condition, etc. In one embodiment, the propylene glycol solvate of celecoxib sodium salt can yield a PXRD pattern with the absence or presence of a peak at 8.21 degrees 2-theta. In another embodiment, the propylene glycol solvate of celecoxib sodium salt can yield a PXRD pattern with the absence or presence of a peak at 8.79 degrees 2-theta.

Example 2 Celecoxib Potassium Salt PG Solvate

A propylene glycol solvate of the potassium salt of celecoxib was prepared. To a solution of celecoxib (253 mg, 0.664 mmol) in diethyl ether (6 mL) was added propylene glycol (0.075 mL, 1.02 mmol). To the clear solution was added potassium t-butoxide in tetrahydrofuran (THF) (1 M, 0.66 mL, 0.66 mmol). Crystals immediately began to form. After 5 minutes, the solid had completely crystallized. The solid was collected by filtration and was washed with additional diethyl ether (10 mL). The white solid was then air-dried and collected. The crystalline salt form was found to be a 1:1 propylene glycol solvate of celecoxib K salt. The solid was characterized by TGA and PXRD. The results are depicted in FIGS. 3 and 4.

FIG. 3 shows the results of TGA. A weight loss of about 14.94% was observed between about 65 and about 250 degrees C. which is consistent with 1 molar equivalent of propylene glycol to celecoxib K. FIG. 4 shows the results of PXRD. Peaks, in 2-theta angles, that can be used to characterize the solvate include any 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 of the following: 3.75, 7.47, 11.33, 14.89, 15.65, 18.31, 20.49, 21.73, 22.51, and 24.97 degrees or any one or any combination of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more peaks of FIG. 4.

Example 3 Celecoxib Lithium Salt PG Solvate

A propylene glycol solvate of the lithium salt of celecoxib was prepared. To a solution of celecoxib (264 mg, 0.693 mmol) in diethyl ether (8 mL) was added propylene glycol (0.075 mL, 1.02 mmol). To the clear solution was added t-butyl lithium in pentane (1.7 M, 0.40 mL, 0.68 mmol). A brown solid formed immediately but dissolved within one minute which subsequently yielded a white fluffy solid. The white solid crystallized completely after 10 minutes. The solid was collected by filtration and was washed with additional diethyl ether (10 mL). The white solid was then air-dried and collected. The crystalline salt form was found to be a 1:1 propylene glycol solvate of celecoxib Li. The solid was characterized by TGA and PXRD.

The results of TGA are depicted in FIG. 5 and show a weight loss of about 16.3% between 50 degrees C. and 210 degrees C. which is consistent with 1 molar equivalent of propylene glycol to celecoxib Li. The results of PXRD are shown in FIG. 6. Characteristic peaks of 2-theta angles that can be used to characterize the salt include any one, or combination of any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 of 3.79, 7.51, 8.19, 9.83, 11.41, 15.93, 18.29, 19.19, 19.87, 20.63, 22.01, or 25.09 degrees or any one or any combination of peaks of FIG. 6.

Example 4 Naproxen Sodium Salt PG Solvate

A propylene glycol solvate of a sodium salt of naproxen was prepared. To a solution of naproxen (348 mg, 1.51 mmol) in diethyl ether (10 mL) was added propylene glycol (0.200 ml, 2.72 mmol). To the clear solution was added sodium ethoxide in ethanol (21%, 0.750 mL, 2.01 mmol). The solution became slightly yellow due to the sodium ethoxide. After 1 minute, crystals began to form. After 5 minutes, the solid had completely crystallized. The solid was collected by filtration and was washed with diethyl ether (10 mL). The product was then air-dried and collected. The solvate was 2:1 naproxen Na:propylene glycol. The solid was characterized by TGA and PXRD.

The TGA thermogram of naproxen sodium salt PG solvate is shown in FIG. 7, and indicates a 13.5 percent weight loss between about 75 and 150 degrees C. This weight loss is consistent with a 2:1 naproxen Na:propylene glycol solvate. The PXRD diffractogram of naproxen sodium salt PG solvate is shown in FIG. 8, and shows peaks at 2-theta angles, including but not limited to, 6.67, 9.65, 13.41, 15.77, 18.55, 20.83, 22.79, and 27.17 degrees. Any one, any two, any three, any four, any five, any six, any seven, or all eight of the above peaks or any one or any combination of peaks in FIG. 8 can be used to characterize naproxen sodium salt PG solvate.

Example 5 Preparation of Olanzapine PG Solvate

Olanzapine PG solvate was prepared by dissolving 1.05 g of olanzapine form I in 8 mL of isopropylacetate and 2.0 mL of propylene glycol with heating. The hot liquid was filtered through a 0.2 micrometer nylon syringe filter. Crystallization occurred after cooling to room temperature. The addition of a small amount of seed crystals from a previous reaction followed by sonication for 10 seconds also facilitated crystallization. Olanzapine PG solvate was isolated by suction filtration, rinsed with isopropylacetate and allowed to air dry. The product was a fine yellow powder. The crystals grew in three dimensions, yielding chunks.

A second preparation of olanzapine form I PG solvate was completed by dissolving 16.2 mg of olanzapine form I in 0.05 ml of propylene glycol and 0.05 ml of isopropylacetate with heating. The sample was cooled to room temperature and a single crystal from a previous preparation was added. The sample was allowed to sit undisturbed for 2 days during which an aggregate clump of several large crystals grew. The crystals were transferred to filter paper, rinsed with a single drop of isopropylacetate, and dried by dabbing with the filter paper. The rinse procedure was repeated a total of four times with fresh filter paper. Characterization of the product has been achieved via TGA, DSC, PXRD, and Raman spectroscopy.

Results from TGA analysis show an 18.05% weight loss representing loss of about 1 equivalent of propylene glycol (FIG. 9). Results from DSC show a peak endothermic transition at 92.63 degrees C. (FIG. 10).

The PXRD pattern has characteristic peaks as shown for two sample preparations in FIGS. 11A and 11B. Peaks can be seen at 2-theta angles including but not limited to 8.33, 8.95, 11.75, 14.47, 15.61, 17.95, 19.21, 19.57, 20.65, 21.41, 22.03, and 23.29 in FIG. 11A. The crystal can be characterized by any one, any two, any three, any four, any 5, any 6, any 7, any 8, any 9, any 10, any 11, or all 12 of the peaks above or one or a combination of peaks in FIG. 11A. In the second representative sample, peaks can be seen at 2-theta angles including, but not limited to, 8.39, 8.89, 13.95, 14.45, 15.55, 17.91, 19.13, 19.55, 20.61, 21.47, 22.07, and 23.31 in FIG. 11B. The crystal can be characterized by any one, any two, any three, any four, any 5, any 6, any 7, any 8, any 9, any 10, any 11, or all 12 of the peaks above or one or a combination of peaks in FIG. 11B.

Single-crystal x-ray studies of olanzapine form I PG solvate were also completed. FIG. 12 shows a packing diagram of the single-crystal structure of olanzapine form I PG solvate. The unit cell data are as follows: space group P2(1)/c, A=10.4264(9), B=13.3916(11), C=14.4424(12), Alpha=90, Beta=95.503(2), Gamma=90, Volume=2007.2(3).

Example 6 Preparation of Cortisone Acetate PG Solvate

Cortisone acetate PG solvate was prepared by dissolving 9.7 mg cortisone acetate in 0.6 mL propylene glycol with heating. Needle-like crystals formed upon cooling, followed by the conversion to large, very thin, rectangular plates over a couple hours.

A second preparation of cortisone acetate PG solvate was completed by dissolving 11.9 mg cortisone acetate in 0.7 mL isopropylacetate with heating to reflux. Upon crystal formation, 0.05 mL propylene glycol was added, heated to reflux to dissolve, and crystals again formed. The resultant crystals were collected and analyzed by PXRD, TGA, and DSC.

A third preparation of cortisone acetate PG solvate was completed by dissolving 65.8 mg cortisone acetate in 7.0 mL isopropylacetate and 0.05 mL propylene glycol with heating. The mixture was cooled slightly and seed crystals from a previous reaction (second preparation above) were added. The resultant crystals form rods, or long rectangular plates that are birefringent when viewed by plane polarized microscopy. Crystals were harvested after 30 minutes and analyzed by single crystal x-ray. Prior to PXRD measurement, the sample was ground, transferred to a vial, and left open to the atmosphere for 4 days.

Results from TGA analysis show a 15.9% weight loss at temperatures up to 150 degrees C. (FIG. 13). 14.9% weight loss occurred between 70 and 150 degrees C. while up to 1.2% weight loss occurred at lower temperatures. This weight loss is representative of a cortisone acetate PG solvate with 1.0 equivalents of propylene glycol. DSC was completed in a closed, not sealed aluminium pan from room temperature to 300 degrees C. at 10 degrees/minute (FIG. 14). The compound was discovered to have two endothermic transitions, one at 148 degrees C. with an intensity of 146 J/g, and the second at 237 degrees C. with an intensity of 77 J/g.

The PXRD of cortisone acetate PG solvate crystallized from isopropylacetate/propylene glycol solution is shown in two diffractograms in FIG. 15A and FIG. 15B. Peaks can be seen at 2-theta angles including, but not limited to, 5.31, 10.71, 14.54, 15.66, 18.49, 21.33, and 23.49 degrees. The crystal can be characterized by any one, any two, any three, any four, any five, any six, or any seven, or any combination of the peaks listed above or one or a combination of peaks listed in FIG. 15A. In the second representative sample, peaks can be seen at 2-theta angles including, but not limited to, 5.29, 10.73, 14.57, 15.69, 18.51, 21.39, 23.51, and 27.49 in FIG. 15B. The crystal can be characterized by any one, any two, any three, any four, any 5, any 6, any 7, or all 8 of the peaks above or one or a combination of peaks in FIG. 15B. FIG. 16 shows a PXRD diffractogram of material crystallized from isopropylacetate alone. This is provided only to differentiate the PG solvate from the unsolvated form of the API.

Single-crystal x-ray studies of cortisone acetate PG solvate were also completed. FIG. 17 shows a packing diagram of the single-crystal structure of cortisone acetate PG solvate. The unit cell data are as follows: space group P2(1), A=9.728(2), B=7.6306(15), C=16.454(3), Alpha=90, Beta=92.568(4), Gamma=90, Volume=1220.2(4).

Example 7 Celecoxib Sodium PG Solvate Trihydrate Preparation:

Celecoxib Na propylene glycol trihydrate was formed by allowing the celecoxib sodium salt propylene glycol solvate to sit at 60% RH and 20 degrees C. for 3 days. (Note: Formation of the trihydrate at 75% and 40 degrees C. occurs as well). The trihydrate begins to form somewhere between 31 and 40% RH at room temperature.

The solid was characterized by TGA and PXRD, which are shown in FIGS. 18 and 19, respectively. FIG. 18 shows the results of the TGA where 9.64% weight loss was observed between room temperature and 60 degrees C. and 13.6% weight loss was observed between 60 degrees C. and 175 degrees C. The PXRD pattern has characteristic peaks at 2-theta angles shown in FIG. 19. Any 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more peaks can be used to characterize the trihydrate, including for example, peaks at 3.47, 6.97, 10.37, 13.97, 16.41, 19.45, 21.29, 22.69, 23.87, and 25.75 degrees. A 0.8 mm collimator was used during acquisition of the diffractogram.

The trihydrate can also be formed by crystallization of celecoxib Na propylene glycol solvate in the presence of H₂O. To a solution of celecoxib (136.2 mg; 0.357 mmol) in diethyl ether (6.0 mL), water (0.025 mL; 1.39 mmol), and propylene glycol (0.030 mL; 0.408 mmol) was added sodium ethoxide in ethanol (21 wt. %; 0.135 mL; 0.362 mmol). A solid formed within one minute and was isolated via filtration. The solid was then washed with additional diethyl ether (2.0 mL) and allowed to air dry. This procedure gives essentially the same PXRD pattern but there is a slight excess of water, which is probably surface water.

The solid was characterized by TGA and PXRD, which are shown in FIGS. 20 and 21, respectively. FIG. 20 shows the results of TGA where 10.92% weight loss was observed between room temperature and 50 degrees C. and 12.95% weight loss was observed between 50 degrees C. and 195 degrees C. The PXRD pattern has characteristic peaks at 2-theta angles shown in FIG. 21. Any 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, or more peaks can be used to characterize the trihydrate, including for example, peaks at 3.43, 6.95, 10.25, 13.95, 16.39, 17.39, 17.75, 18.21, 19.43, 21.21, 22.61, and 25.71 degrees. A 0.8 mm collimator was used during acquisition of the diffractogram.

FIGS. 22-24 have been included as reference PXRD diffractograms. FIG. 22 shows the PXRD diffractogram of celecoxib sodium salt. FIG. 23 shows the PXRD diffractogram of celecoxib lithium salt. FIG. 24 shows the PXRD diffractogram of celecoxib potassium salt. Dynamic moisture sorption studies of several embodiments of the present invention have been discussed in PCT/US03/XXXXX filed on Dec. 24, 2003, entitled “Pharmaceutical Compositions With Improved Dissolution” (Attorney Docket No. TPI-1700CXC2 PCT) by Tawa et al, which is hereby incorporated by reference, in its entirety. Dynamic moisture sorption studies can be used to illustrate important characteristics of the solvates of the present invention, such as decreased hygroscopicity or increased form stability.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. 

1. A pharmaceutical composition comprising a form of a propylene glycol solvate of an active pharmaceutical ingredient (API) selected from olanzapine, cortisone acetate, naproxen, celecoxib trihydrate, celecoxib or salts thereof.
 2. The composition according to claim 1, wherein said form is a propylene glycol solvate of a calcium salt of celecoxib and the composition is characterized by a PXRD pattern comprising peaks expressed in terms of 2-theta angles, said PXRD pattern comprising any 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 of the following: 3.75, 7.47, 11.33, 14.89, 15.65, 18.31, 20.49, 21.73, 22.51 or 24.97.
 3. The composition according to claim 1, wherein said form is a propylene glycol solvate of a lithium salt of celecoxib and the composition is characterized by a PXRD pattern comprising peaks expressed in terms of 2-theta angles, said PXRD pattern comprising any 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 of 3.79, 7.51, 8.19, 9.83, 11.41, 15.93, 18.29, 19.19, 19.87, 20.63, 22.01 or 25.09. 